The developers behind ad-tracking browser plug-in Ghostery said they'd logged 137 different trackers on the Microsoft website and 107 on Apple's site, while they logged 66 on Samsung's site and 65 on HP's. Dell has 106. All of these tech sites make greater use of trackers associated with behavioural advertising than specialist retail sites such as Tesco (64), John Lewis (46) and Dabs (12).